My knowledge of electronics does not exceed beyond P = V I and light switches. however im working on a mechanical based project that includes a tiny electronic circuit to be built.

I visited a local electronics shop but the shop owner refused to give me "free lessons" and asked me to google the parts I need before going back.

long story short:

I need a electronic motor with a diameter of less than 4 cm to rotate clockwise and counter clockwise via a switch. Itd be nice to control the speed of rotation on both directions. ultimately the rotating motor is supposed to turn a metal rod thatd be connected to it.

If anyone can tell me what parts do I need to purchase and how to assemble such a circuit, it would be very helpful.

PS: If you decide to help, please do with details as I don't know anything about electronics.

I'm not sure how detailed you are asking for, but provided your motor is a brushed DC motor, an H-bridge will allow for reversible directions from a single supply(battery). A 555 can be used to generate a Pulse-Width Modulated(PWM) control signal to control the speed of the motor, and a potentiometer can be used to set the pulse-width of the PWM signal so as to set the speed. A DPST switch can be used to set the direction of the motor...

sounds like your local electronics guy is a bit of a d-bag and likely doesn't even know jack about electronics, which is why he told you to google and find out what parts you need because he couldn't assemble them anyway.
I'd tell him you're googling and then going to give your business to another company.

Need more info though what voltage are the motors running at, what will they actually be doing?

sounds like your local electronics guy is a bit of a d-bag and likely doesn't even know jack about electronics, which is why he told you to google and find out what parts you need because he couldn't assemble them anyway.

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I think that's an unfair assumption. If his local electronics store is anything like mine, it's one guy behind a counter who is responsible for large arrays of ICs and various components. If there are other people that could need help, it doesn't make sense to sit and explain the theory of electronics to someone, from a business point of view.

The size or weight of the metal rod would be helpful.
Tiny DC motors usually spin really fast. Several thousand RPM is a common speed. Is that your goal?
Well, of course you want to adjust to low speeds, but how fast is "fast" to you?

You can go to a hobby store and buy the kind of controller that's made for model trains. They typically run a motor of just the size that you've talking about, in both directions. If a speed control knob and a direction switch is all you need, that would do the whole job for you.

I think that's an unfair assumption. If his local electronics store is anything like mine, it's one guy behind a counter who is responsible for large arrays of ICs and various components. If there are other people that could need help, it doesn't make sense to sit and explain the theory of electronics to someone, from a business point of view.

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Maybe it's just me then, but we have only 2 electronics suppliers here where you can buy all the components you need.

Both places are exactly as you say, one guy behind the counter, but each store has a couple of employees.

They are always willing to help out as much as possible and have decent knowledge of electronics.

so yeah from my POV it seems like a dbag move to say "no free lessons, google what you need then come back"

The rod is mounted axially to the shaft of the motor, or along the axis of the motor shaft.

In that case it won't take much motor to turn it, but it's going to take support at both ends to not bend the motor shaft, but I'm sure you already knew that.

what kind of shaver?? like electric hair clipper things? those motors vibrate, they aren't motors as far as I know.

Why not use the motor from one of those small electric screw drivers. they should be about the right size, turn slowly and have plenty of torque. plus it would come with speed adjustment as well as a reversal switch and run from a battery.

The Electronic Goldmine has several motors that might work, G 17949, & G18120 under 4 cm dia with heafty output shafts. Believe shaver, old one, used 5 AA Ni-Cd's for 6 V, +-. If you have a charger might go for Ni-Mh giving roughly 2 to 3 hours run time. RPM is much more understandable than verry slow. Is there any load on the rod? Not part of a wench?